Project Summary/Abstract Approximately 9% of the United States population will develop a kidney stone in their lifetime. Lifestyle factors, genetics, and diet all contribute to the development of kidney stones. The most common type of kidney stone is comprised of calcium oxalate (CaOx) crystals. Research on kidney stones is hampered by limited access to kidney cells and tissue from patients. Very few studies have focused on circulating immune cells which may play a role in disease processes. Monocytes/macrophages are essential for crystal clearance and are recruited to the renal interstitium. We recently determined that monocytes but not lymphocytes or platelets have lower mitochondrial function in patients with CaOx kidney stones compared to healthy subjects. The objective of the current proposal is to evaluate for changes in mitochondrial function, oxidative stress, and inflammatory responses in circulating monocytes and plasma from a large cohort of patients with CaOx kidney stones and healthy subjects. This may identify specific responses associated with this disease. The central hypothesis of the current proposal is circulating monocytes in patients with CaOx kidney stones develop mitochondrial dysfunction due to cellular events mediated by CaOx stones and/or exposure to CaOx crystals in the nephron. This hypothesis will be tested by pursuing three specific aims: 1) Determine whether mitochondrial dysfunction, oxidative stress, and inflammation are associated with circulating monocyte subtypes in patients with CaOx kidney stones; 2) Elucidate whether cytokines or CaOx crystals induce NLRP3 inflammasome pathways and mitochondrial dysfunction in primary monocytes and a human derived monocyte cell line; and 3) Determine whether a dietary oxalate load that produces urinary CaOx crystals in healthy subjects causes similar monocyte responses to those observed in patients. The proposed studies may provide new insights regarding the role of monocyte function and inflammation in CaOx kidney stone disease. This research plan will allow the applicant to gain additional experience in kidney stone disease and clinical research plus training in mass spectrometry, renal pathophysiology, immunology, and biostatistics through practical experience, course work, and guidance from an experienced mentoring team. It will also advance and facilitate the success of the applicant to transition into becoming an independent and productive NIH-funded investigator focused on monocytes and kidney stone disease.